https://theconversation.com/six-things-americans-should-know-about-mass-shootings-48934
#5: Not all mass shootings are terrorism
Journalists sometimes describe mass shooting as a form of domestic terrorism. This connection may be misleading.
There is no doubt that mass shootings are “terrifying” and “terrorize” the community where they have happened. However, not all active shooters involved in mass shooting have a political message or cause.
For example, the church shooting in Charleston, South Carolina in June 2015 was a hate crime but was not judged by the federal government to be a terrorist act.
The majority of active shooters are linked to mental health issues, bullying and disgruntled employees. Active shooters may be motivated by a variety of personal or political motivations, usually not aimed at weakening government legitimacy. Frequent motivations are revenge or a quest for power.